You’ll receive a daily e-mail featuring 50 to 90 percent off on local restaurants, pro-sports tickets, massages, spa treatments, sailboat tours, and more. With Groupon—available in more than 140 cities—you use your credit card to reserve your claim on the day’s group bargain (say, a $10 coupon good for 50 percent off a restaurant meal worth $50 or more). The coupon is activated only if enough people sign on—the number needed varies—but since the site has grown in popularity, the deals almost always get activated. If the deal is on, your credit card will be charged. You can then use the discount anytime over the next six months to a year.